Along with being a faithful companion of food poisoning, oysters have a well-established reputation for enhancing the libido of lovers. But is there any hard evidence behind this claim or is it just the stuff of dating advice columns and seafood marketing boards?

There’s a long history of slurping oysters to boost sexual performance. Some say they were the go-to aphrodisiac for Roman Emperors, while other anecdotes claim the notorious 18th-century lover-boy Giacomo Casanova consumed dozens of oysters each morning to prepare him for a day’s work. Centuries on, tabloid newspapers will still run stories boldly claiming "scientists prove, beyond any doubt, oysters make you horny" and the likes. These reports, however, are often not quite as simple as they seem.

Much of the hype centers around zinc. Oysters have by far more zinc than any other food, with a cooked 3-ounce serving of oysters containing some 74.1 milligrams of the mineral, 673 percent of an average daily recommended intake. It's a mineral that’s essential for male sexual function and fertility. Some studies have indicated that zinc supplementation could boost sperm quality, while other research has suggested low levels of the mineral may decrease testosterone levels and cause abnormalities in sperm quality. 

Testosterone is an important sex hormone that plays a number of roles, including libido. In men, it’s produced in the testicles and is important in sperm production, but women also produce small amounts of the hormone, which influences their sex drive.

Bivalve mollusks (marine and freshwater mollusks including clams, mussels, scallops, and oysters) had also been found to be especially rich in D-Aspartic acid. This amino acid can help to increase the release of a hormone in the brain that eventually aids testosterone production. 

However, there’s very limited evidence that this directly links these foods and their nutrients to increased sex drive or “better” sexual performance. If there are any benefits to be had, which is by no means proven, then it’s likely to be the positive effects of a long-term balanced diet; guzzling oyster after oyster one evening isn’t going to help your health too much, but a diverse and nutrient-rich diet will.

So, if you’re on a romantic date with one thing on your mind, there’s very little nutritional evidence that ordering the oysters will enhance your plans later that evening. Nevertheless, let’s not forget the power of the mind. Placebos are known to work especially well with boosting sexual desire. Given the cultural connection and long history of oysters being considered an aphrodisiac, perhaps their much-touted effects are not just an empty promise. 

"There's an amazing placebo effect with aphrodisiacs," Nancy Amy, a nutritionist and toxicologist at the University of California, told WIRED in 2016. "It's very culturally specific and there's no scientific evidence, but if you think it's going to work, then there's already a 50 percent chance that it will."